Field of the Invention
The present invention relates generally to an optoelectronic identification system for use in identifying a disposable component, and more particularly to a system for identifying which of a plurality of different disposable cassettes is installed onto a main pump unit by using an optical sensor unit on the main pump unit which provides a plurality of light beams in pathways to light detectors, with the cassette having optical identifying indicia which either pass or do not pass the light beams to the sensors.
In the past there have been two primary techniques which have been used to deliver drugs which may not be orally ingested to a patient. The first such technique is through an injection, or shot, using a syringe and needle which delivers a large dosage at relatively infrequent intervals to the patient. This technique is not always satisfactory, particularly when the drug being administered is potentially lethal, has negative side effects when delivered in a large dosage, or must be delivered more or less continuously to achieve the desired therapeutic effect. This problem results in smaller injections being given at more frequent intervals, a compromise approach not yielding satisfactory results.
Alternatively, the second technique involves administering a continuous flow of medication to the patient, typically through an IV bottle. Medication may also be delivered through an IV system with an injection being made into a complex maze of IV tubes, hoses, and other paraphernalia. With drop counters being used to meter the amount of bulk fluid delivered, many medications still end up being administered in a large dosage through an injection into the IV lines, although the medications may be diluted somewhat by the bulk fluid.
As an alternative to these two techniques of administering medication to a patient, the relatively recent addition of medication infusion pumps has come as a welcome improvement. Medication infusion pumps are utilized to administer drugs to a patient in small, metered doses at frequent intervals or, alternatively, in the case of some devices, at a low but essentially continuous rate. Infusion pump therapy may be electronically controlled to deliver precise, metered doses at exactly determined intervals, thereby providing a beneficial gradual infusion of medication to the patient. In this manner, the infusion pump is able to mimic the natural process whereby chemical balances are maintained more precisely by operating on a continuous time basis.
One of the requirements of a medication infusion system is dictated by the important design consideration of disposability. Since the portion of the device through which medication is pumped must be sterile, in most applications of modern medication infusion equipment some portions of the equipment are used only once and then disposed of, typically at regular intervals such as once daily. It is therefore desirable that the fluid pump portion of the infusion pump device be disposable, with the fluid pump being designed as an attachable cassette which is of inexpensive design, and which is easily installable onto the main pump unit.
It will be perceived that it is desirable to have a simple disposable cassette design to minimize the cost of construction of the cassette, using the minimum number of parts necessary in the design of the cassette. The design of the cassette must be mass producible, and yet result in a uniform cassette which is capable of delivering liquid medication or other therapeutic fluids with a high degree of accuracy. The cassette should include therein more than just a fluid pump; other features which have formerly been included in peripheral devices may be included in the cassette.
It may be recognized by those skilled in the art that it may be desirable to use several different types of disposable cassettes with a medication infusion system. Different disposable cassettes may be used which have different stroke volumes, and special purpose cassettes such as enteral pump cassettes, continuous arterio-venous hemofiltration (CAVH) cassettes, continuous blood sampling cassettes, or autotransfusion cassettes may also be used with a medication infusion system to give it the broadest possible range of uses. The use of the wrong cassette may be dangerous, so it may therefore be perceived that it is desirable to provide means to identify the particular cassette (or cassettes) installed on the main pump unit.
It is therefore the primary objective of the present invention to provide a disposable cassette containing a plurality of identifying bits for use with a main pump unit having apparatus for reading the identifying bits contained on the disposable cassette. The disposable cassette of the present invention will be of an advanced design retaining all of the advantages of such devices known in the past, and will include the identifying bits in an integral fashion in the construction of the cassette. The main pump unit shall contain integrally a sensor which is capable of reading the identifying bits on a disposable cassette installed onto the main pump unit. The process whereby the main pump unit identifies the particular type of disposable cassette installed must be fully automatic, and require no user input whatsoever. In fact, one of the main objects is to avoid the possibility of user error in indicating to the main pump unit what types of cassettes are installed on the main pump unit.
The identification system must meet several other requirements in order to present a system which is practical in addition to being novel. At least several different cassettes must be identifiable by the system, and it is also desirable to utilize a redundant system to minimize the possibility of errors being made in the identification of the cassette when it is installed onto the main pump unit. In addition, the inclusion of the identifying indicia on the disposable cassette must be done in a fashion both minimizing the cost of including the indicia while maximizing the reliability of the system.
Specifically, despite the inclusion of a multiple bit identification indicia on the disposable cassette of the present invention, a minimum number of parts shall be utilized in the construction of the cassette, all of which parts are of inexpensive construction yet affording the assembled cassette the high degree of accuracy which must be retained. No identification system known in the art even comes close to combining these features, or even a majority of the features enumerated above.
The cassette used with the present invention must be of a design which enables it to compete economically with known competing systems. The transducer contained in the main pump unit should also be of economical construction, yet exhibiting high reliability and accuracy of operation. The system must provide an ease of use rivaling the best of such competing systems. The system must accomplish all the above objects in a manner which will retain all of the advantages of reliability, durability, and safety of operation. The cassette identification system of the present invention must provide all of these advantages and overcome the limitations of the background art without incurring any relative disadvantage. All the advantages of the present invention will result in a superior medication infusion system having a number of advantages making the system a highly desirable alternative to systems presently available.